Question 1184670
One can use z, but this is still a t-interval, and there is no reason not to use it.
half-interval for 95% is t(0.975,df=299)*s/sqrt(n)
=1.968*0.042/sqrt(300)
=0.0048
the interval is (0.973 gm, 0.983 gm)
The interval width for z=0.00475 gm, compared to 0.00477 gm for t.